1. Field of the Invention
The present invention relates to a fluid powered apparatus that has application for clamping, punching, and other functions that are necessary in the manufacture and assembly of machines such as automobiles. More particularly, the invention is related to a dual action fluid powered apparatus having two pistons that are spaced apart from one another. The pistons each have a gear rack that meshes with a pinion gear that is common to both gear racks. The pistons are fluid powered and are capable of having tools attached thereto. A fluid force may be applied to one or both pistons, depending upon the application and the task that is being performed.
2. Description of the Prior Art
The prior art reveals a wide variety of devices that employ rack and pinion gears to change arcuate motion to a translatory function, or vice versa. In general, most of the prior art devices utilize the pinion gear shaft to supply power to the device or else take power out via the pinion shaft. The majority of the prior art devices employ a rack gear that is formed from plate or bar stock.
The present invention differs from the rack and pinion gear driven machine tool that is shown and described in U.S. Pat. No. 3,722,711 entitled "Machine Tool" issued Mar. 27, 1973, to William B. Seidel. The machine tool has a pair of tool receiving arms that are driven in part by a rack and pinion gear assembly. FIG. 4 of the drawings in U.S. Pat. No. 3,722,711 shows a view in cross-section of the mounting block and the cylinder piston that are mounted in spaced apart and parallel arrangement to one another. A shaft 32 is positioned between the spaced apart pistons. The shaft contains teeth that mesh with a linear array of teeth that are contained on each piston. The pistons are contained entirely within the bores in the housing.
During the operation of the machine tool, a fluid such as air is introduced behind the first piston causing it to move. The rack gear formed on the piston interacts with the intermeshed pinion gear and its attached shaft, causing it to rotate and deliver power to the remainder of the machine tool. The first piston chamber is then vented and fluid pressure is then applied to the second piston, thus causing it to rotate the intermesh pinion gear and its attached shaft in the opposite direction.
Thus, the present invention differs from the previously described machine tool in that both ends of the piston are not confined within the piston housing. There is a direct connection of the pistons to a tool positioned outside the housing. Also, the device of U.S. Pat. No. 3,722,711 is utilized strictly as a power source to rotate a shaft that has a pinion gear formed on the end thereof.
In U.S. Pat. No. 2,818,002 entitled "Transfer Machines" issued Dec. 31, 1957, to Barker et al, there is shown a transfer machine that uses a plurality of clamps to hold a workpiece. The jaws of the clamps are moved toward and away from one another by a series of rack and pinion devices. FIG. 3 of the invention shows in detail two rack and pinion assemblies. The lower rack and pinion assembly contains a piston coupled to a piston rod that serves as a tooth containing rack gear. A pinion gear 68 is keyed to a shaft 69. When pressure is applied to the piston 65, the linear movement of the rack gear is transferred to arcuate movement through the pinion gear, causing the shaft attached thereto to rotate and deliver power to another section of the machine.
In a somewhat similar application, the upper rack and pinion assembly shown in FIG. 3 of U.S. Pat. No. 2,818,002 utilizes a closed piston chamber of cylindrical configuration. The piston confined within the chamber has a rack gear located between the opposed piston heads. The pinion gear is fixed to a shaft. During the operation of the transfer machine, hydraulic fluid is first introduced at one end of the piston to drive it in a forward direction, causing the pinion gear containing shaft to rotate. Hydraulic fluid is then introduced to the other end of the piston rod, causing the piston to move in a reverse direction. Consequently, the pinion gear containing shaft reverses its rotation.
The transfer machine set forth above utilizes but a single piston shaft that is adapted for the application of a pressure inducing force at either end. In both adaptations of the rack and pinion gear driven devices shown in U.S. Pat. No. 2,818,002, the primary purpose was to power a shaft connected to the pinion gear. Also, there are no attachments affixed to the ends of the pistons which are fully contained within the piston chambers.
An adaptation of a rack and pinion gear driven device is shown in U.S. Pat. No. 2,595,131 entitled "Load Grip Means for Trucks and the Like" issued Apr. 29, 1952 to Leslie G. Ehmann. FIG. 1 of Ehmann depicts a pair of spaced apart parallelly oriented cylinders 26. In cross-section, the cylinders are square in configuration and have a cylindrical bore located along the longitudinal axis of the cylinder. One of the four sides of each cylinder contains a rack gear. The rack gears mesh with the teeth of a pinion gear that is attached to a flange. Each one of the cylinders is powered by a piston that is connected to a piston rod. The ends of the piston rods are fixed, thus when fluid pressure is applied to the piston head, the cylinder with its attached rack gear moves in a linear direction. The pinion gear is fixed against rotation by its attached flange. Consequently, when fluid pressure is applied to the piston heads, the rack containing cylinders walk around the teeth of the fixed pinion gear. In this manner, a torque is developed to rotate the entire plate to which the cylinders and their accompanying pistons are attached.
The present invention differs from the above described device in that the ends of the pistons most remote from the end where the fluid pressure is applied are free to move into and out of engagement with a workpiece. The cylinder bores of the present invention are contained within a common block, fixing the direction taken by the pistons and their accompanying rack gears.